Transcription is the process of making an RNA copy of the DNA in order to make protein via translation. These steps form is the central doctrine or "dogma" of molecular biology:

RNA acts as the intermediate between our DNA, which is kept protected in the nucleus, and proteins which are made from the instructions coded in the DNA using machinery loacted int he cell cytoplasm. Appropriately, the type of RNA involved here is called messenger RNA (mRNA).

Only one of the two DNA strands is copied at any one time during the transcription of a gene and it is called the template or antisense strand. The other strand is called the sense, coding or mRNA-like strand. The mRNA strand has the same sequence as the sense strand - except that it is RNA not DNA. The traditional way of drawing the features of a DNA sequence (e.g. genes, promoters, binding sites etc) is to use the sense or mRNA-like strand.

During the first step, or initiation, a proteins, called transcription factors (TF) bind to the double-stranded DNA (dsDNA) at a specific sequence region called the promoter. A DNA dependent RNA polymerase (DDRP) enzyme which recognises a promoter-binding factor called sigma is then guided to the right start position. TF aid the DDRP by interacting directly; by binding to other TFs to construct the basal transcription apparatus or by binding to other DNA sequences. The final step is transcription termination in which another factor, called rho, binds to the mRNA (remember sigma bound to the DNA) and destabilises the DDRP halting transcription. The mRNA grows in a 5' to 3' direction as the DDRP adds ribonucleotides.

The process of transcription is influenced by many other factors that may act directly or indirectly through another molecule to influence the construction and function of the basal transcription apparatus in a positive or negative fashion. Most interations induce further transcription rather than repress it. These upstream factors are unique to each promoter however they are found commonly within the cell. A factor capable of affecting transcription that is produced as a result of some stimulus is called an inducible factor.

Transcription is controlled in many ways. Alterations to the amount of each TF, the rate of transcript processing, the stability of the transcripts all affect the overall rate of transcription.

Three types of DDRP exist within eukaryotes that are called RNA polymerase I, II and III. RNA Pol I produces the 28S, 18S and 5.8S ribosomal RNA (rRNA) fragments, RNA Pol II produces messenger and small nuclear RNA (mRNA and snRNA) and RNA Pol III produces some ribosomal RNA (rRNA) and all transfer RNA (tRNA). The covalent addition of nucleotides creates a short DNA oligonucleotide.